fix: fix audio Mixer freeze

kernel/src/Drivers/Audio/Mixer.cpp

@@ -383,17 +383,36 @@ namespace Drivers::Audio::Mixer {
         g_lock.Acquire();
         VirtualStream& s = g_streams[handle];
         bool changed = false;
+        // Pull the ring pointer out of the slot before freeing it. Once
+        // s.active=false and s.ring=nullptr are visible under the lock no
+        // other path can reach this pointer, so the actual PFA free can run
+        // with the lock released — keeping the HDA buffer-complete IRQ from
+        // spinning on g_lock while ReallocConsecutive walks the free list.
+        int16_t* ringToFree = nullptr;
+        bool lastStream = false;
         if (s.active) {
-            FreeRing(s.ring);
+            ringToFree = s.ring;
             s.ring = nullptr;
             s.active = false;
             s.ownerPid = 0;
             s.name[0] = '\0';
             if (g_activeCount > 0) g_activeCount--;
+            lastStream = (g_activeCount == 0);
             BumpSerialLocked();
             changed = true;
         }
+        // Quiesce the hardware when the final virtual stream goes away so
+        // the HDA DMA ring stops looping its last 32 KiB of samples. The
+        // next Open() reopens the HDA stream via EnsureHdaOpen().
+        bool closeHda = lastStream && g_hdaOpened;
+        int hdaHandle = g_hdaHandle;
+        if (closeHda) {
+            g_hdaOpened = false;
+            g_hdaHandle = -1;
+        }
         g_lock.Release();
+        if (closeHda) IntelHda::Close(hdaHandle);
+        if (ringToFree) FreeRing(ringToFree);
         if (changed) Sched::WakeObjectWaiters((void*)&g_serial);
     }
 
@@ -495,12 +514,14 @@ namespace Drivers::Audio::Mixer {
     }
 
     void CleanupProcess(int pid) {
+        int16_t* ringsToFree[MAX_STREAMS] = {};
+        int ringCount = 0;
         g_lock.Acquire();
         bool changed = false;
         for (int i = 0; i < MAX_STREAMS; i++) {
             VirtualStream& s = g_streams[i];
             if (s.active && s.ownerPid == pid) {
-                FreeRing(s.ring);
+                ringsToFree[ringCount++] = s.ring;
                 s.ring = nullptr;
                 s.active = false;
                 s.ownerPid = 0;
@@ -509,8 +530,16 @@ namespace Drivers::Audio::Mixer {
                 changed = true;
             }
         }
+        bool closeHda = changed && (g_activeCount == 0) && g_hdaOpened;
+        int hdaHandle = g_hdaHandle;
+        if (closeHda) {
+            g_hdaOpened = false;
+            g_hdaHandle = -1;
+        }
         if (changed) BumpSerialLocked();
         g_lock.Release();
+        if (closeHda) IntelHda::Close(hdaHandle);
+        for (int i = 0; i < ringCount; i++) FreeRing(ringsToFree[i]);
         if (changed) Sched::WakeObjectWaiters((void*)&g_serial);
     }